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1. Modeling the tunable thermal conductivity of intercalated layered materials with three-directional anisotropic phonon dispersion and relaxation times

   https://doi.org/10.1039/D1TC05369H  

   Wang, Chengjie; He, Maogang; Liu, Xiangyang; Malen, Jonathan A. (August 2022, Journal of Materials Chemistry C)

   An analytical model using three-directional anisotropic (TDA) dispersion and a novel anisotropic relaxation time (RT) relation for modeling the thermal conductivity ( k ) of intercalated layered materials is developed. The TDA dispersion eliminates the restriction of in-plane isotropy and is suitable for TDA materials such as black phosphorous. We compare calculations of k of bulk intercalated layered materials using the isotropic Debye dispersion and BvK dispersion with our TDA dispersion model, paired with both isotropic and anisotropic RTs. We find that calculated k values by the TDA dispersion model agree best with the experimental data. Furthermore, anisotropic RTs largely improve the performance of the Debye and BvK dispersion models whose average relative deviations for the in-plane k are reduced from 17.3% and 23.0% to 4.4% and 8.5%, respectively. Finally, thermal conductivity accumulation functions of intercalated MoS 2 and graphite are numerically calculated based on the TDA dispersion with anisotropic RTs. These models predict that intercalants cause increased contributions from phonons with shorter mean free paths, especially for in-plane thermal conductivity. 

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2. Modeling method for concentric ring resonators with dispersion engineering

   https://doi.org/10.1364/OE.577296  

   Hasan, Mehedi; Baek, Seungyup; Bernussi, Ayrton; Kim, Sangsik (November 2025, Optics Express)

   We introduce a geometry-guided design method in concentric ring resonators for dispersion engineering. Using eigenmode simulations of a single ring, we construct a two-dimensional round-trip optical path length (OPL) map that systematically identifies phase-matched geometries without exhaustive parameter sweeps. The OPL map finds feasible ring and gap combinations for efficient coupling, also revealing the design limits. With this approach, we design a 50 nm-thick Si₃N₄concentric ring resonator that achieves anomalous dispersion in a weakly-guided mode—a regime that typically exhibits normal dispersion in single-ring configurations. Lugiato–Lefever equation (LLE) simulations confirm that this dispersion-engineered concentric ring can support a bright soliton in a weakly guided mode, overcoming the dispersion limit due to a weak confinement. The proposed modeling method is generalized and readily extendable to a wide range of material platforms and wavelength regimes, providing a powerful tool for diverse integrated nonlinear photonic applications. 

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3. Quartic Kerr cavity combs: bright and dark solitons

   https://doi.org/10.1364/OL.455944  

   Parra-Rivas, Pedro; Hetzel, Sabrina; Kartashov, Yaroslav_V; de_Córdoba, Pedro_Fernández; Alberto_Conejero, J.; Aceves, Alejandro; Milián, Carles (May 2022, Optics Letters)

   We theoretically investigate the dynamics, bifurcation structure, and stability of localized states in Kerr cavities driven at the pure fourth-order dispersion point. Both the normal and anomalous group velocity dispersion regimes are analyzed, highlighting the main differences from the standard second-order dispersion case. In the anomalous regime, single and multi-peak localized states exist and are stable over a much wider region of the parameter space. In the normal dispersion regime, stable narrow bright solitons exist. Some of our findings can be understood using a new, to the best of our knowledge, scenario reported here for the spatial eigenvalues, which imposes oscillatory tails to all localized states. 

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4. Characterizing the dispersion behavior of poly-atomic magnetic metamaterials

   https://doi.org/10.1038/s41598-024-67248-7  

   Jenkins, Connor; Kiourti, Asimina (December 2024, Scientific Reports)

   Abstract The propagation of magnetoinductive (MI) waves across magnetic metamaterials known as magnetoinductive waveguides (MIWs) has been an area of interest for many applications due to the flexible design and low-loss performance in challenging radio-frequency (RF) environments. Thus far, the dispersion behavior of MIWs has been limited to mono- and diatomic geometries. In this work, we present a recursive method to generate the dispersion equation for a general poly-atomic MIW. This recursive method greatly simplifies the ability to create closed-form dispersion equations for unique poly-atomic MIW geometries versus the previous method. To demonstrate, four MIW geometries that have been selected for their unique symmetries are analyzed using the recursive method. Using applicable simplifications brought on by the geometric symmetries, a closed-form dispersion equation is reported for each case. The equations are then validated numerically and show excellent agreement in all four cases. This work simultaneously aids in the further development of MIW theory and offers new avenues for MIW design in the presented dispersion equations. 

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5. The NANOGrav 12.5-Year Data Set: Dispersion Measure Misestimations with Varying Bandwidths

   https://doi.org/10.3847/1538-4357/ad2858  

   Sosa_Fiscella, Sophia Valentina; Lam, Michael T; Arzoumanian, Zaven; Blumer, Harsha; Brook, Paul R; Cromartie, H Thankful; DeCesar, Megan E; Demorest, Paul B; Dolch, Timothy; Ellis, Justin A; et al (April 2024, The Astrophysical Journal)

   Abstract Noise characterization for pulsar-timing applications accounts for interstellar dispersion by assuming a known frequency dependence of the delay it introduces in the times of arrival (TOAs). However, calculations of this delay suffer from misestimations due to other chromatic effects in the observations. The precision in modeling dispersion is dependent on the observed bandwidth. In this work, we calculate the offsets in infinite-frequency TOAs due to misestimations in the modeling of dispersion when using varying bandwidths at the Green Bank Telescope. We use a set of broadband observations of PSR J1643−1224, a pulsar with unusual chromatic timing behavior. We artificially restricted these observations to a narrowband frequency range, then used both the broad- and narrowband data sets to calculate residuals with a timing model that does not account for time variations in the dispersion. By fitting the resulting residuals to a dispersion model and comparing the fits, we quantify the error introduced in the timing parameters due to using a reduced frequency range. Moreover, by calculating the autocovariance function of the parameters, we obtained a characteristic timescale over which the dispersion misestimates are correlated. For PSR J1643−1224, which has one of the highest dispersion measures (DM) in the NANOGrav pulsar timing array, we find that the infinite-frequency TOAs suffer from a systematic offset of ∼22μs due to incomplete frequency sampling, with correlations over about one month. For lower-DM pulsars, the offset is ∼7μs. This error quantification can be used to provide more robust noise modeling in the NANOGrav data, thereby increasing the sensitivity and improving the parameter estimation in gravitational wave searches. 

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